Publicize Bug

When publicizing new Posts via the JetPack Publicize feature (e.g. on twitter), but not using wp.me shortlinks, JetPack prefers the “raw” guid-parameter link (?p=1234) over the permalink (e.g. /2013/04/perma-link-to-post.html).

I don’t think this is “expected behaviour” – Yes, the guid-parameter version is shorter, but that doesn’t matter… On Twitter, there is a character limit, but hyperlinks are always 25chars long (I guess), as they shortlink the URL via t.co anyways.
The Result: Not using wp.me, publicize uses the guid-link. On Twitter, users will access the hyperlink, going from t.co to the guid-link, this one redirecting to the permalink (if enabled).

Or in a nutshell: ugly and inefficient.

I wasn’t able to actually determine the function causing this in jetpack’s sources, so I don’t know if it’s jetpack doing this, some wordpress core-function or the wordpress.com publishing-service application.
Any idea where this comes from, or better: how to change it?

Thanks a lot!
I looked for a solution like this 3-4 Weeks ago, but didn’t find anything that would solve this. I even looked in the Plugin API reference to see if there is a hook to intercept. Still, I can’t find get_shortlink there…
The wp_get_shortlink wiki/codex page also has no information about this filter.